The present invention relates generally to controlling movement of a cutting tool in a high speed cutting machine and more particularly to a method and system for providing a tool path for the cutting tool of the high speed cutting machine.
The recent advent of high speed cutting machines has opened up the possibility of machining a workpiece at a much faster rate than conventional machines allow. Because modem high speed cutting machines are capable of providing spinning rates upward of 40,000 rpm, even a small change of tool load on a cutting tool may damage the cutting tool or workpiece. In particular, in absence of sufficient dissipation of heat generated through the contact of the cutting tool with the workpiece, damage to the cutting tool (such as melting of the tool) or the workpiece is likely.
Many users of high speed cutting machines employ Computer Aided Manufacturing (CAM) systems for controlling the machines. Such CAM systems operate the cutting machines at much lower spinning rates than the capability of the machines, because conventional CAM systems are not suitable for ensuring the conditions for safe operation of the machines (such as constant tool load and efficient heat dissipation). As a result, the machines may not be operated at their full potential. Although some CAM systems provide limited support for roughing the workpiece, this limited support works only in connection with very few workpiece. These conventional roughing capabilities are of little use as the geometries of the workpiece become more complex.
The present invention provides a method and system for controlling movement of a cutting tool of a high speed cutting machine. More particularly, the present invention provides a tool path for the cutting tool spinning at a high rate with minimal risk of damage to the cutting tool and/or a workpiece. To avoid damaging the cutting tool and/or a workpiece, the present invention ensures that a constant tool load is maintained for the cutting tool as the tool travels along the cutting path. In addition, a constant removal rate of material from a workpiece is maintained so that extreme cutting forces are prevented from harming the cutting tool.
Another object of the present invention is to provide a method and system for controlling a cutting tool of a high speed cutting machine that leads to an efficient dissipation of heat generated through contact of the cutting tool with the workpiece. To achieve an efficient heat dissipation, the present invention provides a tool path along which the cutting tool travels to remove material from the workpiece with a constant chip size so as to enhance the transfer of the heat to chip.
In accordance with one aspect of the present invention, a computer-implemented method for machining selected portions of a workpiece by a cutting tool of a high speed cutting machine is provided. The workpiece is imaginarily divided into horizontal slices. The horizontal slice is a unit for the cutting tool to remove material from the workpiece at a time. One of the horizontal slices of the workpiece is selected. The boundary of the slice is determined and subsequent boundaries are determined by assuming material removal from the slice by a cutting depth of the cutting tool buried in the workpiece from the previous boundary. A tool path is generated based on the boundaries of the selected portions of the slice and the cutting tool path is positioned in the air from the boundaries depending on the radius of the cutting tool and a predetermined value of the cutting depth of the cutting tool. The selected portions are machined by moving the cutting tool along said generated tool path.
In accordance with another aspect of the present invention, a controller for controlling a cutting tool of a high speed cutting machine is provided. The controller includes a memory element and a processor. The memory element stores instructions for controlling the cutting tool and data regarding the workpiece for controlling the cutting tool. The processor executes the instructions stored in the memory element for controlling signals for a tool path of the cutting tool. The processor generates data for horizontal slice of the workpiece using the data regarding the workpiece stored in the memory. The processor examines the data for a slice of the workpiece to determine an initial boundary of the selected portion of the slice. The processor generates subsequent boundary data of the selected portions of the slice based on the initial boundary data. The subsequent boundary data may be determined by subtracting the cutting depth of the cutting tool buried in the workpiece from the previous boundary data. The processor generates signals for a tool path, where the tool path is positioned in the air remote from the boundaries depending on the radius of the cutting tool and a predetermined value of the cutting depth of the cutting tool.
The present invention implements a computerized cutting method and system to provide an accurate, efficient and robust tool path along which the cutting tool machines the workpiece under a constant tool load and a constant chip size. Furthermore, the present invention provides a cutting method and system for controlling a cutting tool that are applicable to any geometry of a final product, regardless of the complexity of geometry in a workpiece. The cutting method and system of the present invention are applicable even to a workpiece with no boundary that is open to the air and to any geometry of a workpiece, regardless of the number and location of areas of the workpiece that are not to be removed.